Ingredients
1/4 cup warm water
1 quarter-ounce envelope dry yeast (1 scant tablespoon)
1 cup milk
1/3 cup unsalted butter
1/2 cup sugar
1 1/2 tablespoons coarse salt
1 teaspoon ground cardamom
2 cups cooked sweet potatoes (about 2 medium)
1 teaspoon freshly squeezed lemon juice
1 large egg, lightly beaten
7 cups sifted all-purpose flour
Vegetable oil, for bowl
Melted butter, for brushing
Preparation
Place the warm water in a small bowl, and sprinkle with yeast. Let stand until yeast is dissolved and mixture is foamy, about 7 minutes.
In a small saucepan, heat milk over medium heat just until it begins to steam and bubble around the sides. Remove from heat; add the butter, and stir until melted and combined. Stir in sugar, salt, and cardamom. Let cool slightly.
Preheat oven to 400 degrees. Line a baking sheet with parchment paper; set aside. Combine sweet potatoes and lemon juice in the bowl of an electric mixer fitted with the paddle attachment; beat until smooth, 2 to 3 minutes. Beat in egg and milk and yeast mixtures until smooth.
Switch to the dough-hook attachment. Add flour, 1 cup at a time, beating until a stiff dough forms. Continue kneading dough on medium speed until smooth, about 8 minutes. The dough will still be slightly sticky.
Transfer to a large oiled bowl. Cover with a clean kitchen towel, and let stand in a warm place to rise until dough is doubled in bulk, about 1 hour.
Punch down dough, and knead again with your hands, just until smooth. Using a bench scraper or sharp knife, cut dough into 20 equal pieces, and shape into rolls.
Place rolls on prepared baking sheet, about 2 inches apart; cover with a kitchen towel, and let rise again in a warm place until doubled in bulk, about 40 minutes.
Using kitchen scissors or a sharp paring knife, snip an X in the top of each roll. Brush rolls with melted butter. Bake until tops of rolls are golden, about 20 minutes, rotating pan halfway through. Transfer to a wire rack; serve hot or at room temperature.
